Power-operated reciprocating tool with integral bearing block



Feb. 23, 1965 s. H. KOHLER ETAL 3,170,496

POWER-OPERATED RECIPROCATING TOOL WITH INTEGRAL BEARING BLOCK Filed Oct. 2, 1962 3 Sheets-Sheet 1 SAMUEL H. KOHLER ALLEN C. STANLEY ATTORNEY 3 Sheets-Sheet 2 INVENTORS SAMUEL H. KOHLER ALLEN c. STANLEY ATTORNEY Feb. 23, 1965 s. H. KOHLER ETAL POWER-OPERATED RECIPROCATING TOOL WITH INTEGRAL BEARING BLOCK Filed Oct. 2, 1962 1965 s. H. KOHLER ETAL 3,

POWEROPERATED RECIPROCATING TOOL WITH INTEGRAL BEARING BLOCK 5 Sheets-Sheet 3 Filed Oct. 2, 1962 FIG. IO

INVENTORS SAMUEL H. KOHLER ALLEN C. STANLEY 10 llm BY z wmwafiww ATTORNEY housing for the tool. v v,

It is yet another obje'ctof the present invention to provide, in a'portable power-driven tool havingfa motor 3,170,496 Patented Feb.'23, 1965 3,170,496 POWER-OPERATED RECIPROCATING TOOL WITH INTEGRAL BEARING BLOCK 7 Samuel H. Kohler, Luther-ville, and Allen C. Stanley,

Baltimore, Md., assignors to Black and Decker Manufactoring Company, Towson, Md., a corporation of Maryland Filed Oct. 2, 1962, Ser. No. 227,950

10 Claims. (Cl. 143--68 The present invention relates to an integral bearing block for a reciprocating assembly used in a power-perated device, and more particularly, to a one-piece bearing block which journals a reciprocating shaft in the housing, yet simultaneously supports the shaft assembly from the twisting about itsaxis. It is an object of the present invention to provide, in a portable power-driven tool of the type havinga splithousing including a pair of complementary mating halves, a 'bearing block having a bore formed therein'for journaling a reciprocating shaft, wherein the bearing block is trapped or otherwise retained between the complementary mating halves as the halves are secured t0- gether; and wherein the bearing block has a pair of integrally formed co-planar'guideways extending beyond the bore, and one on each side of the reciprocating shaft, such that atransverse yoke, which is carried by the reciprocating' shaft, rides upon the co-planar guideways as the shaft is reciprocated.

It is anotherobject of the presentjinvention to provide, in a portable power-driven'tool, a bearing block for jour- 'naling a reciprocating shaft, wherein means are provided to prevent the reciprocating shaft from substantial move ment about its axis and with respect to the bearing block; and wherein means arefur ther provided to prevent the bearing block itself from movementwith respectIto ;.the

shaft, a bearingblock for journaling a reciprocating shaft,

' in combination with an intermediate bearing block disposed between the reciprocating shaft and the motor shaft,

motor shaft and a stub'shaft, respectively; and wherein motion-translating.means are provided between the re ciprocating shaft and a gear carried by the stub shaft.-

'It is: yet still another'object of the present invention to provide, in a portable power-driven tool of the typ'ehaving a split-housing including a pair of complementary mating halves, a bearing block trapped between the mat ing halves of the split-housing, wherein at least one 'lon-. gitudinal ridge is integrally formed within one ;of the mating halves; and wherein the longitudinal ridge wili be pinched against'tlie bearing block and will be deformed, as the halves are secured together, thereby trapping and retaining the bearing block between the comple-,

United, States Patent Office mon "longitudinal midplane.

tion along an arc whose radius is substantially equal to that of the circular cross-section of the reciprocating shaft, suchthatthe second pair of guideways further support the reciprocating shaft. 7 I a In accordance withthe teachings of the present invention, there is illustrated and described herein a preferred embodiment in which a portable power-driven tool, such as a portable electric jig saw, is provided with a splithousing including a pair of complementary mating halves, one'of which constitutes the cover for'the other. 'Means are provided to secure the halves together along acorn- A motor is provided 'which has a motor shaft whose axis of rotation is substantially. within the common longitudinalrmidplane. Abearing block" is disposed forwardly of. the motor shaft andis trapped between the complementary matinghalves of the split housing as the halves are secured together. The bearing blockihas a bore formed therein along an' axis' which is within the common longitudinal midplane, and preferably, substantially transverse to the axisof the motor shaft. A reciprocating shaft is journaled in the bore of the bearing block. An intermediate bearing block is disposed between the reciprocating shaft-and the motor. The intermediate bearing'block has a pair of parallel spaced-apart bores formed therein, including a first bore and a second bore,-havingrespective axes which are substantially within the common longitudinalmidplane, and

which are parallel to the axis o frrotation of the motor the gear and the reciprocatingfshaft. This motion-translatingmeans comprises an eccentricpin carried"by the gear and guided'within a transverse yoke,'-thei-yol e being securedto thereciprocatingv shaft. "The bearing block Y has a pair of co-planar guideways integrally formed time 5 wherein the intermediate bearing block has a pair of parallelspaced-apart bores "formed therein for journaling the with and extending beyond the bore formed therein for journaling the reciprocatingijshaft. The co-planar guideways are in a plane which is substantiallytransverse'to the common longitudinal midpla'neof the tool, as well as being parallel to theaxis of the bore; andone each of the co-planar guideways is located on'a respective sideof the reciprocating shaft." The tra'n'sverse yoke',twhich' is carried by the reciprocating shaft, ridesupon the pai'r of co-planar guidewaysas the reciprocating is'reciprocated. Consequently, the reciprocating shaft is held against'substantial movement'about itsown axis and with respect to the bearing block. ''Moreover, -andpreferably;

the, bearing block is formedwithyatleast oneipa'ir of exmentary matinghalves of thesplit-housing;

.It is a further object of the present invention topro-- ent invention, ,with'parts being broken away andsectioned ciprocating shaft, such that the transverse yoke rides on the co-planar guideways as the reciprocating shaft is reciprocated; and wherein thebearing means further has a second pair of guideways, one each alongside of a respective one of the co-planar guideways, and each of the second pair of guideways being coterminous with the bore in the bearing means, that it, formed in cross-secternal flats, radially. of the borer-in .th'e bearing-block; with the result thatthe bearing blockis itself held against movement with respect =toythe split-housing for the 'tool.

These and other objectsof the'present sinyentionwill becomeiapparentwith a'r'eading'of the fol1owing'."specificonjunction with ith'ei enclosed: drawings, I

cation, taken in inwhich1fi".

- FIGURE 1 is a side elevational view of atypical power-driven tool. embodying the teachings'of the presto-iillustrateits design and' construction;

FIGURE 2 is'a transverse section taken alon'gthe lines 22 of FIGURE 1, looking rearwardly of the tool, and showing theintermediate bearing block retained between themating halves "of the split-housing; I I

FIGURE 3 a transverse section taken along the lines 3 -3 of FIGURE 1,10'oking rearwardly of the tool, and

showing the gear that'is' carried by the stub shaft for en gagernent with the pinionformed on the motor shaft;

I o c d FIGURE '4-is 'a transverse section taken along the lines 4-4 of FIGURE 1, looking forwardly of the tool, and

showing the channel-shaped transverse yoke which is secured to thereciprocating shaft, the latter being jour-t naledrin a bore formedrin the bearing block;-

FIGURE 5 is 'a view taken along the rinsess of FIGURE 1, showing the eccentric pin and roller guided withi'n'the transverse yoke, and. further showing the re ciprocating shaft journaled and supportedlin the bearing b1ock,'the transverse yoke ridingv upon the pair of. coplanar guideways formed integrally with the bearing block;

FIGURE 6 is a view taken along the lines 66 of With reference to FIGURES 1, 4, 6, and 5 3,21" hear, ing block 20 is provided for'journaling the reciprocating shaft 12.v The bearing block 20 'is trapped between the mating halves21 and 22 of the split-housing as these,

halves are secured together. The mating half 21"may be referred to as the, bottom half, while the .other mating half 22 may be referredto as the top half or cover; In the assembly'of the jig saw 10, the various components of the jig saw are assembledwithin the bottom half 2'1,'and then the top half 22jis1secured to the bottom half21 bymeans of a plurality of screws 23, which, as shown in FIGURE 6, are received within corresponding tapped'holes 24 formed in the bottom FIGURE-1, enlarged over the scale of FIGURE 1., and

showing the means for trapping the bearing blockbetween the complementary mating halves of the split-housing;

FIGURE 7a is a view corresponding to a portion of FIGURE 4, but enlargedoverythe scale of FIGURE' t, andpwith thetop :half of the split-housing-shown in exploded-relationship to the. bottom half of the splithousing and to the bearing block to be trapped there between; t a is a partial elevational view taken along FIGURE 7b the lines 7b.7b of FIGURE 7a showing thelongitudinal I ridges which are formed in the top .or cover half of the split-housingso as to trap 'the bearing block asrthe complementarymating halves of the split-housing are' secured :together;

FIGURE 70 is .a View corresponding substantiallyto a portion :of FIGURE '70:, ,"but, showing how: the longii tudinal :ri'dg'es willbepinched against the *bearing after the mating halves aresecured't'ogetheri block FIGURE 8' is an exploded perspective view, showing the motor shaft having the pinion formed thereon, the

' intermediate. bearingiblockhaving a first .bore for journalingthe motor'shaft, the-second bore formed in the e intermediat'ebearing block forjournalingthe stub shaft,

, the gear 'carried by the stub shaft, the eccentric pin carried gbiy thezgear, th'e'roller :on the eccentric pin, the

"transverse-yoke carried; by thegreciprocating shaft, ,the bearing block forijournalingnhe reciprocating shaft and conventional) is herein omitted for ease of illustration. The [motor includes as motor shaft (or armature shaft) 7 25, and afan 26 and fan washer 26a aremounted upon the motor shaft 25.. The fan 26' draws cooiing air throughfthe motor housing v11 from the; rearward air ventilating slots ma s the cooling air is discharged forwardly (and radially) of the 1 fan 26 by means of a series of openings, which are herein omitted for ease of illustration, The motor shaft 2'5'projects through an opening formed ina wall128 formedbetwe en the motor housing 11 andthe gear, case 12. Thecmotor shaft 25;

protrudes within tliegear cas 12, and. a pinion'29 is formed on the end of' the motor shaft 25. -Preferably, i but, not necessarily, the pinion 29 is of a helicalcde'sign,

as shown, and is formed integrally with the motor shaft 25.

With {reference again to FIGURES 1 and 8, and with reference to; FIGURES i 2, 3, and 5, an intermediate for simultaneously guidingy the transverse yoke, and a,

which the bearing-block is trapped; v

,,,FIG URE'9a is a view corresponding to a portion FIGURE 7a, but showing a modified: constructionwhich utilizes a pluralitypof cylindricaL,rubberjplugs in lieu of theylongitudinal ridges;

FIGURE 39b is a partial ;elevational view taken-along the linjes ,19b- 9b of FIGURE 9a, showing the cy1in-.

"drical configuration of one ofthe rubber plugs;

, FIGURE; 9c'jcorresponds toFIGURE 9a, but shows portion of, the: bottom }half, of the, split-housing within 7 bearing-1 block- 3t isc disposed between-the reciprocating shaft 13 and the electric. motor. Preferably; the intermediate bearing-block 30has 'acut-out portion 3021 which engages a complementarily' formed .portion 60b of V the housing, thereby assisting in'retainingand securing the intermediate bearing block ssimhe; split-housing. A V V first bore 31 and a second bore 32 are formed in the 7 intermediate bearingblock 3.0. TheQbores'IiI and .32 are parallel to each other and are spaced-apart from a 1' 'each other; and the'bores 31,:32shave respective axes how the rubber, plugs wil l;b,e;..compressed when the mat a I ing ha ve es ure tog t er; 1

i FIGUREi 10a is a second modification, wherein the .transversei yoke is secured to the reciprocating shaft in another manner, and wherein the bearing block is changed accordinglyzfor increased supplementary. support of the reciprocating:shaftpand LEIGURE'IObZis-h 'sectionview taken'alohgthe lines lob-Jab OfFIG'URE 10d. 7 h 1 e With reference toiFIG URE 1, there is illustrated a vention arerequally appreciable to a wide varietyiof-portable power-driven tools, appliances, and other devices.

With thi'sjn' mind, the portable electric jig saw 10 cornprisesanmotorhousing (11, a gear case 12 forwardly of themotonzhousing 11, a reciprocating shaft 13, a saw' blade 14 secured" thereto-by means-of a clamp .15, a supporting shoe-16 by means of which thesaw'10 may be guided along the top surface of a suitable workpiece, andan overhead handle 17: whichvincludes an electric switch 18and a conventional .line cord 19,"thc latter beingbroken'for ease of illustration.

, ing block; to the bottomjhalfll of the split-housing. I

which ar e substantially-Within the common longitudinal midplane AB, and which are parallel to the E'axis. of rotation -of the motorshaft-ZS: Atransversehole :33 is formed in the intermediate bearing block 30 between the bores 'S-LandSZq A screw- 34, s'eeIFIGURE'Z, passes through the transverse hole 33*and engagesfwitliin a tappedrecess 35, thereby securing theintermediate bear- Prefer abl-y, but not necessarily, the intermediate bearing .h owever it will be appreciated that other methods for producingjthese bearing blocks, as well as variousother' l materials, are within the scope of'the present .invention.

; Moreoverjit will be fu'rther appreciated that the interportable iel'ectric jig saw 10,"although itwillbe appret eiated .that the teachihgs ande'ssence ofthe present in-J block :30, as wel11'asthe bearing block 29, are formed from an cil-impregnated porous material, such as a bronze-iron composition that is sintered from a powder;

mediate bearing block 30, like the bearing block 20,

couldv also be trapped, 'if-desiredfbetween the mating halves 21, 22 of the split housing for thetool 1h. The motor shaft ZSjisijournaled Within the first bore 31 of the intermediate bearing block 3t), and a stubshaft 36 isjournaled Within thessecond 'bore 32 of- 'the intermediate bearing block'30. Afgear'i37 is press-fitted upon:

the stub shaft 3 6;and is carried thereby; for meshing engagement with the pinion 29;- Also, vthe gear"??? is -provided with'a'pair of blind holes 370 drilledithereinv- (see FIGURES 3 and 5) for counterbalancing purposes in a manner understood by one skilled in the art.

With reference again to FIGURES 1, 4, 5,6, and 8, a bore 38 is formed within the bearingblock so as to journal the reciprocating shaft 13. The bore 38 has an axis which is substantially withinthe common longitudinal midplane AB, and which is substantially transverse to the axis of rotation of the motor shaft 25. A transverse yoke 39, which may be channel-shaped, is secured to the shaft 13 by means of a rivet 40; and preferably, the subassembly of the transverse yoke '39, rivet 40 and reciprocating shaft'13 are dip-brazed and simultaneously cyanide-hardened. An eccentric pin 41 is journaled within an'eccentric bore 41a formed within the gear 37; a roller 42 is loosely-carried by the eccentric pin 41, and the roller 42 is guided'within the track formed by the transverse yoke 39. This is the conventional Scotch-yoke type of motion-translation mechanism that is used to convert the rotation of the motor shaft 25 into the reciprocation of the shaft'13.

Moreover, a pair of co-planar guideways 43 and 44 are integrally formed withinthe bearing block 20, which (see FIGURE. 1) is substantially L-shapedin side elevation.

and 44 as -the reciprocatingshaft 13 is reciprocated. Pref- 'erably, the reciprocating shaft 13 is circular in cross-sec- The co-planar. guideways 43 and 44 (see'FIGURE 5) extion'and is tubular (as shown) for decreased Weight. A

V pair of second guideways 45 and 46 are also formed withinthe. bearing block 20. One each of these second guideways 45, 46 are alongsideofa respective one of the pair of coplanar guideways43 and 44, and respective longitudinalledges 47 and'48 are formed therebetween. The

longitudinal ledges 47, 48 serve the purpose of clearance cut-outs, should any of the dip-brazing material adhere to the back'of the yoke 39 adjacentto the reciprocating shaft v13. The second pair ofguidewa'ys 45, 46 are coterminous with the-bore 38 formed in the bearing block20;

, and like the coe'planar 'guideways'43and 44, the'second guideways 45, 46 extend beyond the bore 38. Moreover,"

each of the-second pair of guideways 45, 46 are formed in cross-section alongan arc whose radius is substantially equal to that of the circular cross-section of the reciprocatingshaft 13.

' Accordingly, it will be appreciated that as the'reciprocating shaft llris reciprocated by means of the aforesaid motion-translating mechanism, the reciprocating shaft 13 will be journaled' primarily within the bore 38 and will be "further supporteid tin asllpplementary manner) upon the second guideways 45, 46. At the same time, thetransverse yoke 39, which is carried by the reciprocatingshaft 13, will be supported upon and will ride upon the" co-planar guideways 43;44 'as'the shaft 13 islreciprccated. Consequently, the reciprocating shaft 13is fully journaled and supported; moreover, and by reason of the i transverse yoke 39 riding upton'the co-planar guideways 43 and 44, the reciprocating shaft 13: is simultaneously prevented from substantial movement, such as twisting, about its own axis and with respect to the bearing block With reference again to FIGURE 5, a longitudinal cutout 49 is provided within the bearing block 20, intermediate the second pair of guideways 45 and 46, so as to provide a clearance slot. for the head of therivet-40.

With reference againto FIGURES 4, 6, and 8,,and with further reference to FIGURES 7a, 7b, and 7c, the bearing block 20 is-provided withja pair of parallel flat sides 50 and 51, each of which lies within a respective plane that is substantially parallel to thecommon longitudinal midbearing block 20 from movement about the axis of the bore 38 formed therein and with respect to the split-housing 21 and 22, thereby further enhancing the stability of the reciprocating shaft 13 and the saw blade 14 which is secured thereto." Moreover, a pair-toflands 52a and 52b are formed in the top half or cover 22, while a corresponding plurality of lands 53a, 53b, and 53c are formed in the bottom half 21. A plurality of longitudinal ridges 54 are formed in the respective lands 52a and 52b of the mating half or top half 22. In an actual embodiment of the present invention, the longitudinal ridges 54 extend approximately or A of an inch beyond their respective lands 52a, 52b; however, in the enclosed drawings, the ridges 54 have been exaggerated slightly for clarity of understanding. As shown more particularly in FIGURES 7a and 7c, the l ongitudinal ridges 54 will be pinched againstthe bearing block 20 as the mating halves'21 and 22 are secured together, thus trapping or retaining the a i bearing block 20 within the split-housing. The longitudinal ridges 54 are formed integrally within'the top half 22,- which preferably is formed from a suitable material such as die-cast aluminum. Consequently, the longitudinal ridges 54 are deformed slightly when pinched against the bearing block 20. More specifically, and as shown in FIG- URE-7c, each longitudinal ridge 54 may have its apex r'ounded'oif slightly as the mating halves 21 and 22 are secured together. Under certain circumstances,- the ridges 54 may create a very slight impression in-tlhe portions of the-bearing block 20 that are engaged thereby, depending upon the respective dimensionsand the relative hardness "one that is-durabl'e and reliable, to be manufactured at a relatively-low unit cost. I a -Moreo ver, the bearing block 20 (radially of its bore 38) is provided With a pair of tapered sides 55:: and SSbfor matching. engagement with correspondingly-tapered re cesses formed integrally within the bottom half 21; and the bearing block 20 is further provided with asecond pair of tapered sides 56a and 56b for matching engage ment with correspondingly-tapered recesses formed-integrally with in the top half '22, thereby assistingj'inthe location and trapping of the bearing block 20."

With references to FIGURES 9a, 9b, and 9c, a modification of the present invention is shown wherein the longitudinal ridges 54havebeen eliminated and have been substituted for by a plurality of rubber plugs 57, Preferably, a pair of rubber plugs 57 are utilized, one ofwhich is located within the land 52a, and the other of which is located within the land 5% (as shown); however, only one of the rubber plugs 57 has been "shownfhere'in for convenience of illustration" The rubber plugs 57 are received within corresponding semi-cylindrical"recesses 58 formed within the top half-22; consequently, and as shown more particularly in FIGURE 90, the rubber plug's 57 are compressed against the'bean'ng block 20 as'the mating halves '21'and 22'are detachably secured together, thereby assisting in the location and trapping of the bearing block20."

With reference to FIGURES 10a and 1011, another modification is shown wherein the transverse yoke 39 is secured tothe reciprocating shaft-13. in a manner other than utilizing the. rivet 40. 'In this instance, the reciprocatingshaft 13 is still tubular-throughout most of its length, preferably, but has a solid top portion 59 having asl-ot 60 formed therein to receive the transverse yoke 39. The yoke 39 is secured to'the shaft 13'by means of a flathead screw 61 which engages a suitable tapped hole 62 formed in the top portion 59 of the reciprocating shaft 13.; Consequently, the longitudinal cut-out '49 maybe eliminated, as well as the longitudinal ledges 47, 48; and

the secondxpair of guideways 45, 46 may be merged into one-continuous; (substantially 'semicylindrical) guideway 63 for increased(supplementary) support of the recipro eating shaft 126,v v

The advantages and features of the present invention may be summarized as follows: (1) the bearing block I I 20, which is substantially L-shaped in longitudinal section,

serves the dual function of both journaling the reciprocating shaft, 13 and simultaneously supporting the yoke 39; (2) inasmuch assthe bearing block 29 is all one is prevented fro-1n twisting about the axis iof reciprocation; V v, 2. In apower-operatedreciprocating tool'of'the type comprising a split housing including a pair of com- I plementary mating portions detachably secured together and further comprising a reciprocating assembly having a reciprocating shaft-and a transverse yoke secured thereto, the yoke haying respective ends projectingjlatpiece, that is, the co-planar guideways-43, 44 are integrally formed with the block which has the bore 38 formed therein, it is not necessary to resort to the prior art practice of machining a separate bearing boss and separate ways in the castingswto close tolerances, but rather, the bearing, block 20 (being integral) may be mounted in the tool 10 independent of any tolerances in the castings 21,-22. of the tool; (3) the bearing block 21) Y istrapped between the mating halves 21, 22 of the split- 7 housing, as the halves are secured together, and any tolerances between the bearing block 20 and the halves 21',

22 are taken up by the longitudinal ridges 54 (or rubber plugs 57) in the cover halfZZ of the split-housing, (4)

the yoke 39 is'fully supported on the co-planar guideways 433,744, and hence the yoke 39 (together with the reciproa V eating shaft Band blade 14) are-prevented from substantial 'movemenh such' as twisting, about the axis of the bore 38 in the bearing block 20; (5) the bearing block 20, being formed with at least one pair of external flats 5t 51, is prevented from movement with respect to themating halves-21, 22 of the split-housing for the tool 10;

(6) both ofithe bearing blocks-2t) and'30 may beformed V by-a sintering process, using ajpowder having a suitablebronze-iron composition, so as to result, ultimately, in oil impregnated porous bearings that are precision components at relatively-low, unit cost; (7) thezcombination of the L-shaped bearing block 20 and the intermediate 1 7 bearing block 30,- the latter having a pair of parallel spacedeapart boresforrned therein, results ina tool (such a as the portable electric jig saw 10) thatiisjcornp-act, dure able, and easy to handleyand (8) the overall combination 7 of structure, in the jig saw 10, allows the unit to be manur factured quickl-yand easily without expensive machining soasto result in areliable high-performance unit at a substantiallylower unit cost. 7 I 7 Obviously, many modifications maybe made without fdeparting from the basic spirit of the presentinvention;

andaocordingly, Within the scope of'the appended claims, V

the invention may be practiced other than has beens'pecifically described.

" We claim: I

l. Ina power operated reciprocating tool of the type comprising a split housing including apair of complementarymating portions detachably secured together, and I further comprisinga reciprocating assembly including a reciprocating shaftwith ;a 'yoke secured thereto, and a tool elementcarried by the reciprocating; shaft beyond the housing, the improvement in journaling the reciprofcatin'g, shaft in the housing and simultaneously supporting thereciprocating assembly from twisting about the axis of. reciprocation which comprises:

(a) a one-plece bearing block and means'to retain said" block between the mating portions of the split housing, and to preventsaidblock from twisting iabout theiaxisof reciprocation} (h said block comprising a body portion formed fwith a borefor-journaling the reciprocating shaft;

and a I i (c). said block further comprising a guideway formed 'inte grally'w ith sai cl -body portion and extending therefrom parallel to the axis of reciprocation;-

:gu'ideway, and whereby the reciprocating assembly (21) whereby the yoke is slidably supported on said' erally of the shaft, and a tool element carried by the reciprocating shaft beyond the housing, the improvement in means to journal the reciprocating in the reciprocating housing and simultaneously to support the shaft" assem:

bly from twisting about the axisjof reciprocation which (0) said block further comprising" a pair of coplanar V guideways formed integrally with said body'portion and extending therefrom parallel to the axis of'reciprocation; s p 7 (d) said co-planar guideways extending one each on a respective side. of the reciprocating shaft,

whereby the respective ends of the-transverse yoke are slidab'ly supported on 'said guidejways, and I 7 ,whereby the reciprocating assembly is prevented 7 from twisting aboutthe; axis-0f reciprocation. 3. .The improvement in claim 2,'wherein:

(q) the reciprocating shaft has a circular cross-sectio'nj and wherein: f -V V (b) said bearing blockhas;-a 'second-pair of guide- 7 ways, one veach adjacent; to said .,coplanar .guid'e-' ways; a 1 I (c) each of said second" pair of guidewaysi'being --forrned as part of' ar'cylindricalsurface coincident f with-said bore'in said bearing blockbodyfthereby further supportingv the reciprocating shaft; r

4;. In a power-operated reciprocating toolof the type comprising a housing. and areciptocatingfassembly infthe housing including separable housing members, the assemblyincluding a reciprocating shaft and a yoke secured to the shaftQthe yOKe'haVing a back portion, and a'front portion including ajtrack for an eccentric, and a 'tool element carriedby the reciprocating shaft beyond the" housing, the improvement in means to journal. the re-' 'ciprocating shaft in-.the housing and; simultaneously to support the,reciprocatingg'assembly, from twisting about 'the. axis of reciprocation which comprises:

7 (a) a one-piece substantiallyl shaped bearing block retalned betweensaid separable housing ,members against substantial twistingabout the .axis of re- (b said block comprising a body portion formed t with a bore forjour-naling therecip rocating shaftg;

' (c) saidbloclcjfurther comprising a first guideway I f ormedflintegrally with said body'por-tion and extending therefrom-parallel to the'axis of 'reciproca tion;- H a .7 (d) said first guideway having a gross-sectional shape fxconforming to that of the backportionof the yoke, whereby the yoke} avoids anybearing contact with said ;separable hotisingniembers, and whereby the j backof lthefyoke is instead-slidablyf supported on said firstiguideway of said'bearing block whereby the reciprocating assembly is thereby preventedfrom substantial twisting about theiaxis .ofreciprocationj and a'secohd guideway'formed integrally with said body and extending therefrom parallel to the axis 1 of" reciprocation "adjacent f said first -guideway; i

(f) said second guideway having a cross-sectional shape conforming to that of the reciprocating shaft itself, whereby the shaft is slidably supported on said second guideway in addition to being journaled in said bore. 7 Y

5. In a power-operated reciprocating tool of the type comprising a housing and a'reciprocating assembly in the housing including separable housing members, the assem- I bly including a reciprocating shaft anda yoke secured to the shaft, the yoke having a back portion and a front por tion including a track for an eccentric, and a tool ele-v ment carried by the reciprocating shaft beyond the housing, the improvement in means to journal the reciprocating 1 shaft in the housing and simultaneously to support the reciprocating assembly from twisting about the axis of said separable housing members, and whereby the respective ends of the yoke are instead slidably sup' portedon said co-planar guideways of said bearing block, and whereby the shaft assembly is thereby prevented from substantial of reciprocation. n 6. In a portable electric jig saw, the combination of i (a) ahousing comprising separable housing members detachably secured together; (b) a reciprocating assembly in saidhousing; saidrassembly comprising: Y (1) a reciprocating shaft; and

(2) a yoke secured to said shaft; g (c) a saw blade secured to said shaft beyond said housing;.

' (d) a bearing block having a borefor journ'aling said reciprocating shaft; 7 I .s (e) means to dispose said block between said separable (1) said block further having an integral guideway formed therein parallel to the axis of reciprocation;

(g) whereby said yoke avoids any bearing contact with either of said housing members and is instead slidably supported on said guideway of said bearing block, and whereby said yoke isthereby precluded from substantial twisting about the axis of'reciprocation.

7. The combination of claim 6, wherein said bearing 10 block comprises:

twisting about the axis housing members and retain said block from substana tial twisting about the axis of reciprocation; and

(a) a sintered oil-impregnated substantially L-shaped bearing member. V

.8'. The combination of claim 6, wherein:

(a) said housing comprises a pair of complementary mating halves detachably secured together along a common longitudinal midplane; and wherein (b) said bearing block is trapped between said matinghalves; s

(c) said block having fiat surfaces formedthereon for engaging complementary recesses in the mating halves of the split housing, thereby preventing said block fromtwisting about the axis of reciprocation.

9. The combination of claim 6, wherein said integral guideway in said bearing block comprises;

(a) a planar guideway; and wherein: (b) the back of said yoke is slidably supported on said planar guideway.

10. The combination of claim 6, wherein said integral guideway in said bearing block comprises:

(a) a pair of co-planar guideways, one on each side of said reciprocating shaft;

(b) whereby the respective ends of the back-of said yoke are slidably supported on said co-planar guideways.

References Cited by the Examiner V UNITED STATES PATENTS 2,606,947 8/52 Happe 308 -184 2,665,960 1/54 Caisley. f I 2,902,067 9/59 Oakley l43t68.6 2,931,926 4/60 De A'ngelis etal 310- 2,988,924 v 6/61 Cooley 'Z450 3,031,990 5/62 Broedner..

ANDREW R. JUHASZ, Primary Examiner.

DQNALDR. SCHRAN,WILLIAM w. DYER, 1a.;

Examiners, I 

1. IN A POWER-OPERATED RECIPROCATING TOOL OF THE TYPE COMPRISING A SPLIT HOUSING INCLUDING A PAIR OF COMPLEMENTARY MATING PORTIONS DETACHABLY SECURED TOGETHER, AND FURTHER COMPRISING A RECIPROCATING ASSEMBLY INCLUDING A RECIPROCATING SHAFT WITH A YOKE SECURED THERETO, AND A TOOL ELEMENT CARRIED BY THE RECIPROCATING SHAFT BEYOND THE HOUSING, THE IMPROVEMENT IN JOURNALING THE RECIPROCATING SHAFT IN THE HOUSING AND SIMULTANEOUSLY SUPPORTING THE RECIPROCATING ASSEMBLY FROM TWISTING ABOUT THE AXIS OF RECIPROCATION WHICH COMPRISES: (A) A ONE-PIECE BEARING BLOCK AND MEANS TO RETAIN SAID BLOCK BETWEEN THE MATING PORTIONS OF THE SPLIT HOUSING, AND TO PREVENT SAID BLOCK FROM TWISTING ABOUT THE AXIS OF RECIPROCATION; (B) SAID BLOCK COMPRISING A BODY PORTION FORMED WITH A BORE FOR JOURNALING THE RECIPROCATING SHAFT; AND (C) SAID BLOCK FURTHER COMPRISING A GUIDEWAY FORMED INTEGRALLY WITH SAID BODY PORTION AND EXTENDING THEREFROM PARALLEL TO THE AXIS OF RECIPROCATION; (D) WHEREBY THE YOKE IS SLIDABLY SUPPORTED ON SAID GUIDEWAY, AND WHEREBY THE RECIPROCATING ASSEMBLY IS PREVENTED FROM TWISTING ABOUT THE AXIS OF RECIPROCATION. 